Fix DPI of QWidget with parent on a different screen

If a floating QWidget has a parent on a different screen, its DPI was
still inherited from the parent instead of taken from the screen.

The only reason we did was in case there is a customDpi set.
(customDpi is a private thing that is only used in designer to change
the appearance of the previewed widget)

So instead of recursing into QWidget::metric for each ancestor, just
use a for loop to find if one parent has a customDpi. If no customDpi
is found, then return the DPI of the right screen.

Task-number: QTBUG-58959
Task-number: QTBUG-48242
Change-Id: Ie6e9e48cdd10234994c0919ba3aea9b0cdb52494
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

1 files changed, 1 insertions, 1 deletions

diff --git a/tests/auto/widgets/kernel/qwidget/tst_qwidget.cpp b/tests/auto/widgets/kernel/qwidget/tst_qwidget.cpp
index 7afa7ca42b..5715505fd6 100644
--- a/tests/auto/widgets/kernel/qwidget/tst_qwidget.cpp
+++ b/tests/auto/widgets/kernel/qwidget/tst_qwidget.cpp
@@ -8181,7 +8181,7 @@ void tst_QWidget::customDpi()
     custom->logicalDpiX();
     QCOMPARE(custom->metricCallCount, 1);
     child->logicalDpiX();
-    QCOMPARE(custom->metricCallCount, 2);
+    QCOMPARE(custom->metricCallCount, 1);
 }
 
 void tst_QWidget::customDpiProperty()